Contact washer system and method for controlling a windscreen wiper motor

ABSTRACT

The present invention relates to a contact-disk system including a control unit, a rotatable contact disk and a plurality of contact elements, the contact disk having a plurality of paths and each contact element being associated with one path. The paths have electrically conductive segments and electrically insulating segments, logical states being encoded by the electrically conductive segments and the electrically insulating segments. The contact disk has n paths with n≧2, and N logic states are encoded by the n paths and by the sequence of the electrically conductive segments and the electrically insulating segments, with N&gt;2 n . The present invention also relates to a method for controlling a windshield-wiper motor and a windshield-wiper motor having a contact-disk system according to the present invention.

[0001] The present invention relates to a contact-disk system having a control unit, a rotatable contact disk and a plurality of contact elements, the contact disk having a plurality of paths and each contact element being associated with one path. The paths have electrically conductive segments and electrically insulating segments, and logic states are encoded in the electrically insulating segments. The present invention also concerns a method for controlling a windshield-wiper motor having a contact-disk system, in which several paths of a rotatable contact disk are contacted by a plurality of contact elements, the paths having electrically conductive segments and electrically insulating segments. Logic states are encoded in the electrically conductive segments and the electrically insulating segments. The present invention also relates to a windshield-wiper motor.

BACKGROUND INFORMATION

[0002] It is known to use generic contact-disk systems for the control of windshield wipers. A contact disk of a generic contact-disk system generally rotates in synchronism with the windshield-wiper motor. Contact elements sweep over the electrically conductive segments and the electrically insulating segments of the contact disk. This provides information about the instantaneous position of the windshield wipers. Generally, for more complicated control processes, i.e., for control processes in which a greater number of windshield-wiper positions are to be encoded, a greater number of paths is required on the contact disk, each of these paths being contacted by at least one contact element.

[0003] For instance, more windshield-wiper states must be encoded for motor vehicles in which not only the trunk lid but also the rear window may be opened. The rear-wiper motors must be designed in such a way that, when opening the rear window, the wiper arm(s) come to rest in an extended end position (EPP) off the window. This function may be achieved, for instance, by a gearless, reversing rear-wiper motor. In the upper and lower reversing position, this motor is electronically reversed in its polarity, either by double relay or semiconductor H-bridge. If a wiper-arm position in the extended park position is desired, which generally is located below the park position, the motor will not be reversed in its polarity in the lower reversing position. It is also possible to use an oscillating gear motor having reversing electronics. In this motor, the upper reversing position and the extended park position are mechanically implemented via the gearing. The lower reversing position and the park position, respectively, are electronically implemented, by the motor being reversed in its polarity in the park position, either by double relay or semiconductor H-bridge.

[0004] To implement this rear-wiper function mentioned by way of example, six different states must be encoded and transmitted to the reversing electronics in the control unit. The following states are involved:

[0005] upper reversing position;

[0006] wiping field;

[0007] segment before park position;

[0008] park position and lower reversing position, respectively;

[0009] segment after park position and between park position and extended park position, respectively;

[0010] extended park position.

[0011] In many cases it is desirable to use contact disks with as few paths as possible. For instance, it may happen that the contact elements, which are generally implemented as sliding contacts, and the contact paths are located on the same side as the conversion gearing of the oscillating gear-motor. In this case, there may only be room for two contact paths on the contact disk. Thus, the number of possible encodings is limited.

SUMMARY OF THE INVENTION

[0012] The present invention builds on the contact-disk system according to the species in that the contact disk n has paths with n≧2 and that logic states are encoded by the n paths and the sequence of electrically conductive segments and the electrically insulating segments N, with N>2^(n). The present invention allows a number of encodings that is appropriate for the respective application, notwithstanding the limited number of contact paths on a contact disk. This is achieved by the control of the contact-disk system not only analyzing the instantaneous logic states, which are generated by the electrically conductive segments and the electrically insulating segments of the contact paths, but by the control unit additionally recording the transitions between the various states.

[0013] Preferably, the contact disk has two paths. In this manner, the contact disk may be used in systems in which the sliding contact and the contact paths are located on the same side as the conversion gearing of the oscillating-drive motor.

[0014] The present invention is particularly advantageous due to the fact that six logic states may be encoded by a contact disk having two paths. If two paths are subdivided into electrically conductive and electrically insulating segments, and if, for instance, the electrically conductive segments are identified by logical 0 and the electrically insulating segments by logical 1, combining these bits will result in 2²=4 encodable states. The present invention makes it possible, for instance, to encode six states and thus provide an advantageous control for a rear-wiper motor including extended park position.

[0015] The present invention is useful particularly due to the fact that a first state corresponds to an upper reversing position, that a second state corresponds to a wiping field, that a third state is a state before a park position, that a fourth state is a park position, that a fifth state is a state after a park position and that a sixth state is an extended park position. These states are sufficient to implement the required windshield-wiper functions that are needed in rear-wiper motors to be used in rear-windows that are capable of being opened.

[0016] It is of particular advantage that, in the first state, one first path is electrically conductive and a second path is electrically insulating, that, in the second state, the first path and the second path are electrically conductive, that, in the third state, the first path and the second path are electrically insulating, that, in the fourth state, the first path is electrically insulating and the second path is electrically conductive, that, in the fifth state, the first path and the second path are electrically conductive, that, in the sixth state, the first path is electrically conductive and the second path is electrically insulating, and that the states occur consecutively in the order of their numbering. For instance, if the fourth state is the park position of the windshield wiper, the contact elements in this state contact one electrically insulating segment of the first path and an electrically conductive segment of the second path. Therefore, the bit combination 1/0 is transmitted to the control unit. If the windshield wiper moves out of the park position in the direction of the wiping field, the control device first receives a bit combination 1/1, corresponding to the third state, and then the bit combination 0/0. However, if the windshield wiper moves out of the park position further towards the extended park position, the bit combination 0/0 is transmitted to the control unit immediately after the bit combination 1/0. Thus, the required information regarding the windshield-wiper states is transmitted to the control unit by the transitions between the states.

[0017] It is particularly advantageous if two contact elements are provided for picking off the state information and if two contact elements are provided for supplying a supply voltage. Two contact elements are sufficient to pick off the state information off the two paths. Two contact elements are useful to supply a supply voltage, since there are states in which not only the first path but also the second path is electrically insulating, which completely insulates segments of the contact disk from one another.

[0018] Preferably, the upper reversing position is mechanically implemented by an oscillating gear; the park position and the extended park position correspond to lower reversing positions, and the lower reversing position in park position is implemented by reversing the polarity of the motor via the control unit. In this manner, the contact-disk system according to the present invention may be used to advantage in connection with an oscillating-gear motor having reversing electronics.

[0019] It is especially preferred if, after switching on the ignition of a motor vehicle, or after preselecting a windshield-wiper function when the wiper-arm position is in the park position, an initialization of the contact-disk system is implemented by leaving the park position and inferring the polarity of the window-wiper motor as a function of the encoding change. In the switched-off state of the ignition of a motor vehicle, the windshield wiper will usually be in the park position. If the ignition is switched on again, the polarity of the windshield-wiper motor is normally not known in the control unit. Therefore, the control unit is also unaware of the movement direction of the windshield wiper. For this purpose, the windshield wiper, with the currently given polarity of the windshield-wiper motor, is shifted out of the park position. As a function of the adjacent encoding, the control unit will then receive information as to the polarity of the motor, so that all information regarding a subsequent operation is available. After the initialization, the windshield wiper may be guided back again to its park position. In order to ensure that the wiper arm sweeps over as small an angle as possible during initialization, the segment of the contact disk for the park position should be selected to be as small as possible.

[0020] The present invention builds on the generic method in that the contact disk n has paths with n≧2 and that logic states are encoded by the n paths and by the sequence of the electrically conductive segments and the electrically insulating segments N, with N>2^(n). The present invention makes it possible to provide a number of encodings that is appropriate for the respective application, despite a limited number of contact paths on a contact disk. This is achieved by the control unit of the contact-disk system not only analyzing the instantaneously given logic states, which are generated by the electrically conductive segments and the electrically insulating segments of the contact paths, but by the control unit also recording the transitions between the various states.

[0021] The method is particularly advantageous when the contact disk has two paths. In this manner, the contact disk may be used in systems in which the sliding contacts and the contact paths are located on the same side as the conversion gearing of the oscillating-drive motor.

[0022] Preferably, six logic states are encoded in case of a contact disk having two paths. If two paths are subdivided into electrically conductive and electrically insulating segments, and if, for instance, the electrically conductive segments are identified by logical 0 and the electrically insulating segments by logical 1, 2²=4 states are encodable by combining these bits. The present invention makes it possible, for instance, to encode six states and thereby provide an advantageous control for a rear-wiper motor including an extended park position.

[0023] Furthermore, the present invention is useful particularly because of the fact that a first state corresponds to an upper reversing position, that a second state corresponds to a wiping field, that a third state is a state before a park position, that a fourth state is a park position, that a fifth state is a state after a park position and that a sixth state is an extended park position. These states are sufficient to implement the required windshield-wiper functions, which are necessary in rear-wiper motors to be used for rear-windows capable of being opened.

[0024] The present invention is particularly advantage because, in the first state, one first path is electrically conductive and a second path is electrically insulating, so that, in the second state, the first path and the second path are electrically conductive, that, in the third state, the first path and the second path are electrically insulating, that, in the fourth state, the first path is electrically insulating and the second path is electrically conductive, that, in the fifth state, the first path and the second path are electrically conductive, that, in the sixth state, the first path is electrically conductive and the second path is electrically insulating, and that the states occur consecutively in the order of their numbering. For instance, if the fourth state is the park position of the windshield wiper, the contact elements contact one electrically insulating segment of the first path and one electrically conductive segment of the second path in this state. Therefore, the bit combination 1/0 is transmitted to the control unit. If the windshield wiper moves out of the park position, in the direction of the wiping field, the control device first receives a bit combination 1/1 corresponding to the third state, and then the bit combination 0/0. However, if the windshield wiper moves from the park position further in the direction of the extended park position, the bit combination 0/0 is transmitted to the control device immediately following the bit combination 1/0. Therefore, the required information regarding the windshield-wiper states is transmitted to the control unit by the transitions between the states.

[0025] Preferably, two contact elements are provided to pick off the state information, and two contact elements are provided to supply a supply voltage. Two contact elements are sufficient to pick off the state information off the two paths. Two contact elements for supplying the supply voltage are useful, since there are states in which not only the first path but also the second path is electrically insulating, which completely insulates segments of the contact disk from one another.

[0026] It is preferred that the upper reversing position is mechanically implemented by an oscillating gear, that the park position and the extended park position correspond to lower reversing positions, and that the reversing position in the park position is implemented by reversing the polarity of the motor via the control system. The electrical polarity reversal is preferably carried out in the park position and the lower reversing position, respectively. In this manner, the contact-disk system according to the present invention may be used to advantage in connection with an oscillating-drive motor having reversing electronics.

[0027] Furthermore, the method is particularly advantageous by the fact that, after switching on the ignition of a motor vehicle, or after preselecting a windshield-wiper function, an initialization of the contact-disk system is implemented by leaving the park position and inferring the polarity of the windshield-wiper motor as a function of the encoding change. The windshield wiper will usually be in the park position when the ignition of a motor vehicle is switched off. If the ignition is then switched on again, the control unit is usually unaware of the polarity of the windshield-wiper motor. Therefore, the movement direction of the windshield wiper is also not known by the control unit. For this purpose, the windshield wiper with the currently given polarity of the windshield-wiper motor is shifted out of the park position. The control system will then receive information regarding the polarity of the motor as a function of the adjacent coding, so that all the information for a later start-up is available. After initialization, the windshield wiper may be guided back to its park position. To ensure that the wiper arm sweeps over the smallest possible angle during initialization, the contact-disk segment for the park position should be selected as small as possible.

[0028] The present invention builds on a generic windshield-washer system in that a contact-disk system is provided in accordance with the present invention. In this way, the advantages of the contact-disk system and the method according to the present invention are implemented in a windshield-wiper motor.

[0029] The present invention is based on the surprising recognition that even in situations where only a limited number of contact paths may be implemented, in particular two contact paths, a sufficient number of states may be encoded, which even allow controlling rear-wiper motors having an extended park position. The present invention may be used in oscillating gear motors having reversing electronics. In addition, the operating method of the washing-water pump may be influenced, by letting current flow only during upward wiping, because bit combination 0/0 is preceded by bit combination 1/1 during upward wiping, while during downward wiping 0/0 follows 0/1 (upper reversing position).

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] With reference to the accompanying drawings, the invention is explained below by way of example on the basis of preferred exemplary embodiments.

[0031] The figures show:

[0032]FIG. 1 a schematic depiction of a plurality of encoded states of a contact-disk system; and

[0033]FIG. 2 a contact disk according to the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0034]FIG. 1 schematically depicts the various logic states of a contact disk. The sectors correspond to the different wiper position as follows: Contact Contact State Path 1 Path 2 A upper reversing position 0 1 B wiping field 0 0 C segment before park position 1 1 D park position 1 0 E segment after park position 0 0 F extended park position 0 1

[0035] The shaded areas in the depiction according to FIG. 1 are electrically conductive. The white segments adjoining the shaded areas are electrically insulating. For instance, the electrically conductive areas are contacted by ground, so that a contact element touching this area will have a ground signal which corresponds to logical 0.

[0036]FIG. 2 shows an exemplary embodiment of a contact disk 10 according to the present invention. Contact disk 10 has two paths 12, 14. These paths are divided into electrically conductive and electrically non-conductive segments, the designations of the segments corresponding to the designations of FIG. 1.

[0037] If the wiper arm is in wiping field B after the ignition is switched on, the control unit sees the bit combination 0/0. Until now, it cannot distinguish between the segment after park position E and wiping field B. In the further course, the wiper moves out of the wiping field, for instance, into the segment before park position C. Therefore, the control unit receives the bit combination 1/1. In this way, it is clear to the control unit that the wiper had initially been in wiping field B. For, if the wiper had been in the segment after park position E, the control would have received a bit combination 1/0, which corresponds to park position D, before receiving the bit combination 1/1.

[0038] It is also possible to implement an initialization on the basis of the given encoding of contact disk 10 after switching on the ignition. If the wiper arm is in park position D after switching on the ignition, it is not clear from the bit combination 1/0 alone, which is transmitted to the control unit in the park position, in which direction the wiper arm moves, since the polarity of the motor is not known. Therefore, current is supplied to the motor after switching on the ignition until park-position segment D is left. By the unambiguous encoding of the adjacent segments, the segment before park position C (1/1), on the one hand, and the segment after park position E (0/0), on the other hand, the control unit immediately determines in which direction the wiper arm is moving at the given polarity. This information is stored, and the polarity of the motor is reversed again, so that the wiper arm is moved back into park position D. It is useful for this initialization to select the segment of park position D as small as possible, so that the wiper arm preferably sweeps over as small an angle as possible. It is also possible to optionally implement the initialization after switching on the ignition or after selecting a windshield-wiper function.

[0039] Upper reversing position A has the coding 0/1. If this information is forwarded to the motor, the motor will not be reversed in its polarity. Instead, the direction of rotation of the contact disk will be maintained, since the wiper arm is mechanically reversed in the upper reversing position A via the oscillating gear. If upper reversing position A is left, the contact disk supplies the bit combination 0/0 in the further course and then the bit combination 1/1, which unambiguously informs the control unit that park position D is being approached, starting from the upper reversing position A. If, after switching on the ignition, the wiper arm were in segment E after the park position, park position D would be reached after letting current flow into the motor, without the bit combination 1/1 occurring for the segment before park position C. Here, too, the direction would be determined in an unambiguous manner.

[0040] The preceding description of the exemplary embodiments according to the present invention is for illustrative purposes only, and is not meant to restrict the invention. Various changes and modifications are possible within the framework of the present invention, without leaving the scope of the present invention and its equivalents. 

What is claimed is:
 1. A contact-disk system, comprising a control unit, a rotatable contact disk (10) and a plurality of contact elements, the contact disk (10) having a plurality of paths (12, 14) and each contact element being associated with one path (12, 14), the paths having electrically conductive segments (A1, B1, B2, D2, E1, E2, F1) and electrically insulating segments (A2, C1, C2, D1, F2), and logic states being encoded by the electrically conductive segments (A₁, B₁, B₂, D₂, E₁, E₂, F₁) and the electrically insulating segments (A₂, C₁, C₂, D₁, F₂), wherein the contact disk (10) has n paths (12, 14), with n≧2, and N logic states are encoded by the n paths (12, 14) and by the sequence of the electrically conductive segments (A₁, B₁, B₂, D₂, E₁, E₂, F₁) and the electrically insulating segments (A₂, C₁, C₂, D₁, F₂), with N>2^(n).
 2. The contact-disk system as recited in claim 1, wherein the contact disk (10) has two paths (12, 14).
 3. The contact-disk system as recited in claim 1 or 2, wherein six logic states (A, B, C, D, E, F) are encoded in a contact disk (10) having two paths (12, 14).
 4. The contact-disk system as recited in one of the preceding claims, wherein a first state (A) corresponds to an upper reversing position, a second state (B) corresponds to a wiping field, a third state (C) is a state before a park position, a fourth state (D) is a park position, a fifth state (E) is a state after a park position, and a sixth state (F) is an extended park position.
 5. The contact-disk system as recited in one of the preceding claims, wherein in the first state (A), a first path (A₁) is electrically conductive, and a second path (A₂) is electrically insulating, in the second state (B), the first path (B₁) and the second path (B₂) are electrically conductive, in the third state (C), the first path (C₁) and the second path (C₂) are electrically insulating, in the fourth state (D), the first path (D₁) is electrically insulating and the second path (D₂) is electrically conductive, in the fifth state (E), the first path (E₁) and the second path (E₂) are electrically conductive, and in the sixth state (F), the first path (F₁) is electrically conductive and the second path (F₂) is electrically insulating, and the states occur consecutively in the order of their numbering.
 6. The contact-disk system as recited in one of the preceding claims, wherein two contact elements are provided to pick off the state information and two contact elements are provided to supply a supply voltage.
 7. The contact-disk system as recited in one of the preceding claims, wherein the upper reversing position (A) and the lower reversing position EPS (F) are mechanically realized by an oscillating gear, the park position (D) and the extended park position (F) correspond to lower reversing positions, and the lower reversing position is implemented in the park position (D) by reversing the polarity of the motor via the control unit.
 8. The contact-disk system as recited in one of the preceding claims, wherein, after an ignition of a motor vehicle is switched on, or after a windshield-wiper function is preselected while the wiper arm is in the park position, an initialization of the contact-disk system is implemented by leaving the park position (D) and inferring the polarity of the windshield-wiper motor as a function of the coding change.
 9. A method for controlling a windshield-wiper motor having a contact-disk system, in which a plurality of paths (12, 14) of a rotatable contact disk (10) is contacted by a plurality of contact elements, the paths having electrically conductive segments (A₁, B₁, B₂, D₂, E₁, E₂, F₁) and electrically insulating segments (A₂, C₁, C₂, D₁, F₂), and logic states are encoded by the electrically conductive segments (A₁, B₁, B₂, D₂, E₁, E₂, F₁) and the electrically insulating segments (A₂, C₁, C₂, D₁, F₂), wherein the contact disk (10) has n paths (12, 14), with n≧2, and N logic states are encoded by the N paths (12, 14) and by the sequence of electrically conductive segments (A₁, B₁, B2, D₂, E₁, E₂, F₁) and of the electrically insulating segments (A₂, C₁, C₂, D₁, F₂), with N>2^(n).
 10. The method as recited in claim 9, wherein the contact disk (10) includes two paths (12, 14).
 11. The method as recited in claim 9 or 10, wherein six logic states (A, B, C, D, E, F) are encoded in a contact disk (10) having two paths (12, 14).
 12. The method as recited in one of the claims 9 through 11, wherein a first state (A) corresponds to an upper reversing position, a second state (B) corresponds to a wiping field, a third state (C) is a state before a park position, a fourth state (D) is a park position, a fifth state (E) is a state after a park position, and a sixth state (F) is an extended park position,
 13. The method as recited in one of the claims 9 through 12, wherein, in the first state (A), a first path (A₁) is electrically conductive, and a second path (A₂) is electrically insulating, in the second state (B), the first path (B₁) and the second path (B₂) are electrically conductive, in the third state (C), the first path (C₁) and the second path (C₂) are electrically insulating, in the fourth state (D), the first path (D₁) is electrically insulating and the second path (D₂) is electrically conductive, in the fifth state (E), the first path (E₁) and the second path (E₂) are electrically conductive, and in the sixth state (F), the first path (F₁) is electrically conductive and the second path (F₂) is electrically insulating.
 14. The method as recited in one of the claims 9 through 13, wherein two contact elements are provided to pick off the state information and two contact elements are provided to supply a supply voltage.
 15. The method as recited in one of the claims 9 through 14, wherein the upper reversing position (A) is mechanically realized by an oscillating gear, the park position (D) and the extended park position (F) correspond to lower reversing positions, and the lower reversing positions (D, F) are implemented by reversing the polarity of the motor via the control unit.
 16. The method as recited in one of the claims 9 through 15, wherein, after switching on an ignition of a motor vehicle, or after preselecting a windshield-wiper function when the wiper arm is in the park position, an initialization of the contact-disk system is implemented by leaving the park position (D) and inferring the polarity of the windshield-wiper motor as a function of the coding change.
 17. A windshield-wiper motor having a contact-disk system as recited in one of the claims 1 through
 8. 